1. Field of the Invention
This invention relates to rotary variable switches typically used to control the speed of a video cassette recorder.
2. Description of Related Art
When viewing or editing a prerecorded video tape, it is desirable to control the speed of the tape. Video editing equipment typically has a console with a plurality of control switches to vary the frame speed and the audio levels of the picture. In addition to the basic start and stop buttons, most consoles have knobs to control the shuttle speed (fast forward and reverse) and another switch to move the tape from frame to frame, commonly referred to as jogging. Typically, each function is controlled by a different knob. That is, there is usually a start/stop button, a separate knob to control shuttle speed and yet another knob to control the jogging of the film. It would be preferable to incorporate all of these functions in one switch so that the various operating parameters can be controlled by one hand or a pair of fingers, greatly reducing the complexity of use and freeing the other hand to control another function such as sound.
Most switches have upper and lower limits, which for rotary knobs is implemented by limiting the clockwise and counterclockwise rotational travel of the switch. In addition, such switches will have intermediary limits that define different scales within the range of the controlled function. For instance, audio equipment will have a volume knob that rotates and stops at 10, 20 etc, which define the varying levels of sound produced by the system. The upper and intermediary limits of the switch are usually determined and fixed when the unit is constructed. The upper or intermediary limits can not be changed once the switch has been assembled and installed into the equipment. It would be desirable to have a switch with limits that can be varied without mechanically changing the control. This would be particularly useful for a console that can be attached to both video and audio recording equipment, wherein the switch has certain predetermined limits and scales for an audio system and a different set of limits and scales for video equipment.